To assess relationships between changes in adiposity, sex hormones, lipids, lipoproteins, and apolipoproteins, we will quantitate plasma lipids, lipoprotein cholesterols, apolipoproteins, testosterone, estradiol, height and weight every six months for 3 years in 240 black and 240 white males 12-15 years of age at intake. These subjects will be randomly selected from a representative school population. We will also conduct these longitudinal studies in 240 12-15 years old male offspring of parents with premature coronary heart disease (CHD), myocardial infarction and/or coronary bypass surgery Less than or equal to 55 years of age. Recent studies by ourselves and others have shown that 1) offspring of patients with premature heart disease have lipid, lipoprotein, and apolipoprotein profiles placing them at increased future risk to CHD; 2) that lipid, lipoprotein, and apolipoprotein profiles differ in black and white males, with black males having higher HDLC and apoA1, and lower triglycerides; 3) significant decreases in HDLC occur during sexual maturations, primarily related to complex interactions between testosterone, estradiol, and ponderosity; 4) sex hormone profiles in males with early CHD differ from those in healthy controls; and 5) mean estrogen levels in obese males are significantly greater than in non-obese males. These longitudinal studies in a biracial population of 12-15 year old students and offspring of parents with premature CHD, putatively at increased risk to CHD themselves, will permit an assessment of adolescent changes in lipid profiles and relationships of these changes to sex hormones in normal and high risk adolescent males.